Non-shrinking Oil-hardening Steels

Certain steels have a very low rate of expansion and contraction
in hardening and are very desirable for test plugs, gages, punches
and dies, for milling cutters, taps, reamers, hard steel bushings
and similar work.

It is recommended that for forging these steels it be heated slowly
and uniformly to a bright red, but not in a direct flame or blast.
Harden at a dull red heat, about 1,300 deg.F. A clean coal or coke
fire, or a good muffle-gas furnace will give best results. Fish
oil is good for quenching although in some cases warm water will
give excellent results. The steel should be kept moving in the bath
until perfectly cold. Heated and cooled in this way the steel is
very tough, takes a good cutting edge and has very little expansion
or contraction which makes it desirable for long taps where the
accuracy of lead is important.